Rotary compressor

ABSTRACT

A rotary compressor  1  includes a pair of closing members  11  and  12  that close axial front and rear opening portions of a cylinder  5 , and a rotor  6  that is accommodated within the cylinder  5  and rotated by a motor. 
     Concave portions  11 C and  12 C having the same depth are respectively formed in inner wall surfaces  11 A and  12 A of the closing members  11  and  12 , and the concave portions  11 C and  12 C are filled with synthetic resin coatings  22 . Accordingly, the surfaces of the synthetic resin coatings  22  are flush with the inner wall surfaces  11 A and  12 A located outwardly adjacent thereto (a left side in the drawing). 
     The rotary compressor  1  which can prevent a seizure on end surfaces  6 A and  6 B of the rotor  6 , and can be manufactured at low cost can be thereby provided.

TECHNICAL FIELD

The present invention relates to a rotary compressor, and more particularly, to a rotary compressor including a cylindrical cylinder that accommodates a rotatable or swingable rotor, and a pair of closing members that close opening portions at opposite axial ends of the cylinder.

BACKGROUND ART

There has been conventionally known a rotary compressor including a cylinder that is formed in a substantially cylindrical shape, a pair of closing members that close opening portions at opposite axial ends of the cylinder, and a rotor that is accommodated within the cylinder, and rotated or swung in conjunction with a drive shaft (for example, Patent Literatures 1 to 3).

In the conventional rotary compressor as described above, the axial dimension of the rotor is set to be slightly smaller than the axial dimension of the cylinder such that a slight gap is ensured between opposite axial end surfaces of the above rotor and inner wall surfaces (thrust surfaces) of the above closing members respectively located close thereto when assembling of members constituting the rotary compressor is completed.

In the conventional rotary compressor, while heat reception and heat dissipation are conducted between a refrigerant gas and the cylinder or the closing members when the refrigerant gas is sucked into and discharged from a compression space within the cylinder, there is a disadvantage that the volumetric efficiency of the rotary compressor is reduced by the heat reception and the heat dissipation. To solve the problem, for example, Patent Literature 2 proposes a configuration in which a position facing the compression space within the cylinder, i.e., the inner wall surfaces (the thrust surfaces) of the pair of closing members are coated with a synthetic resin (see FIG. 11). Since the compressor in Patent Literature 2 employs the configuration as described above, the volumetric efficiency of the compressor is improved by suppressing the heat reception and the heat dissipation between the refrigerant gas supplied into and discharged from the compression space and the inner wall surfaces of the pair of closing members.

Meanwhile, the above compressor in Patent Literature 2 has a following problem since entire end surfaces as the inner wall surfaces of the pair of front and rear closing members are coated with the synthetic resin. That is, when the cylinder and the two closing members are integrally assembled together by a fastening bolt by closing the axial front and rear opening portions of the cylinder by the pair of closing members as shown in FIG. 11, the synthetic resin coatings on the inner wall surfaces of the two closing members are axially compressed, so that an originally-intended gap a may not be ensured between the opposite axial end surfaces of the rotor and the inner wall surfaces (the synthetic resin coatings) located close thereto. When the originally-intended gap cannot be ensured between the opposite end surfaces of the rotor and the inner wall surfaces (the synthetic resin coatings) located close thereto after the completion of assembling, there is a problem that a seizure occurs between the opposite axial end surfaces of the rotor and the inner wall surfaces (the synthetic resin coatings) in sliding contact therewith during rotation of the rotor.

To solve the problem, in the compressor in Patent Literature 3, the inner wall surfaces of the two closing members are not coated with the synthetic resin at a position in abutment against opposite axial end surfaces of the cylinder so as to prevent the seizure between the opposite end surfaces of the rotor and the inner wall surfaces of the two closing members (see FIG. 12). To be more specific, in Patent Literature 3, annular cutout portions are formed in axial front and rear edge portions in an inner circumferential surface of the cylinder (inner rims of the opposite end surfaces), and the synthetic resin coatings on the two closing members are set to such radial dimensions as to be accommodated in the above annular cutout portions as shown in FIG. 12. By employing the configuration as described above, when the cylinder and the two closing members are assembled together by a fastening bolt as shown in FIG. 12, outer rims of both the synthetic resin coatings are accommodated in the cutout portions, and thus, not axially compressed. Accordingly, in the compressor in Patent Literature 3, the slight gap a is ensured between the opposite axial end surfaces of the rotor and the inner wall surfaces (the thrust surfaces) of the closing members located close thereto after the completion of assembling.

PRIOR ART DOCUMENTS Patent Literature

-   Patent Literature 1: Japanese Patent No. 3742848 -   Patent Literature 2: Japanese Patent Laid-Open No. 57-49084 -   Patent Literature 3: Japanese Patent Laid-Open No. 2010-133346

SUMMARY OF INVENTION Problems to be Solved by the Invention

However, the above compressor in Patent Literature 3 also has a following disadvantage. That is, while it is assumed that the depth (the axial dimension) of the above annular cutout portion is slightly larger than the thickness of the synthetic resin coating accommodated therein, the depth of the cutout portion and the thickness of the synthetic resin coating are actually set to several μm in Patent Literature 3. Thus, it is very complicated to control the dimensions (the depth, the outer diameter) of the above annular cutout portion and the dimensions (the thickness, the outer diameter) of the synthetic resin coating in a manufacturing process of the members constituting the compressor. Since it is also necessary to adjust the dimensional relationship between the above cutout portion and the synthetic resin coating in several-μm units in the manufacturing process, there is also a disadvantage that the manufacturing cost of the compressor is correspondingly increased.

Also, since the above annular cutout portion is formed to such a depth and an outer diameter as to be able to accommodate the outer rim of the synthetic resin coating, a slight gap X is radially and axially generated between the annular cutout portion and the outer rim of the synthetic resin coating accommodated therein (see FIG. 12). When the gap X as described above is generated, the refrigerant gas leaks to a low-pressure space side from a high-pressure space through the above gap X during expansion and contraction of the compression space within the cylinder caused when the rotor is rotated after the completion of assembling, thereby causing a disadvantage that the compression efficiency of the compressor in operation is deteriorated.

Moreover, in the compressor in Patent Literature 3, the outer rim of the synthetic resin coating projects from the original inner wall surface (the end surface) of the closing member to form a step thereon. Thus, when the cylinder and the two closing members are assembled together, the cylinder and the two closing members need to be axially aligned with each other first. The axial alignment operation between the cylinder and the two closing members is complicated since the step as the outer rim of the synthetic resin coating may be caught in the annular cutout portion on the cylinder side in the axial alignment operation. In some cases, the entire outer rim of the synthetic resin coating may not be completely accommodated in the annular cutout portion, so that a portion of the outer rim of the synthetic resin coating may remain displaced outward from the annular cutout portion on the completion of assembling. In this case, there is a disadvantage that the performance of the compressor is deteriorated due to leakage of the refrigerant gas sucked into and discharged from the cylinder, and abnormal wear occurs to cause a seizure when the rotor end surface slides on the synthetic resin coating.

Means for Solving the Problems

In view of the aforementioned circumstances, the present invention according to claim 1 provides a rotary compressor including: a cylindrical cylinder that is arranged within a casing; a pair of closing members that close axial front and rear opening portions of the cylinder; a compression space that is formed by the cylinder and the pair of closing members; and a rotor that is accommodated within the compression space so as to be movable in conjunction with a drive shaft, wherein

a concave portion is formed in a region facing the compression space in an inner wall surface of each of the closing members, and the concave portion is filled with a synthetic resin coating such that a surface of the synthetic resin coating is flush with the original inner wall surface of the closing member located radially outward thereof.

Advantageous Effects of Invention

In accordance with the aforementioned configuration, the dimensions of the concave portion and the synthetic resin coating can be easily controlled in a process for manufacturing the two closing members. Also, the synthetic resin coating in the above concave portion is flush with the inner wall surface, so that a rotary compressor which can prevent a seizure between an end surface of the rotor and the synthetic resin coating as a thrust surface, and can be manufactured at lower cost than conventional compressors can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical sectional view illustrating one embodiment of the present invention.

FIG. 2 is a sectional view of a main portion taken along a line II-II in FIG. 1.

FIG. 3 is an enlarged view of the main portion in FIG. 1.

FIG. 4 is an enlarged view of the main portion in FIG. 3.

FIG. 5 is a horizontal sectional view of a main portion illustrating a second embodiment of the present invention.

FIG. 6 is a vertical sectional view of the main portion in the second embodiment shown in FIG. 5.

FIG. 7 is a sectional view of a main portion in another embodiment of the present invention.

FIG. 8 is a sectional view of a main portion in another embodiment of the present invention.

FIG. 9 is a vertical sectional view of a main portion illustrating another embodiment of the present invention.

FIG. 10 is a front view of a main portion illustrating another embodiment of the present invention.

FIG. 11 is a sectional view illustrating a conventional technique disclosed in Patent Literature 2.

FIG. 12 is a sectional view illustrating a conventional technique disclosed in Patent Literature 3.

MODE FOR CARRYING OUT THE INVENTION

To describe the present invention below based on embodiments shown in the drawings, reference numeral 1 in FIGS. 1 and 2 denotes a rotary compressor, and the rotary compressor 1 is mainly used for domestic or industrial air conditioners, and in FIGS. 5, 6, and 8, mainly used for automotive air conditioners.

The rotary compressor 1 includes a motor 3 as a drive source that is accommodated in an upper portion within a sealed casing 2, and a compression mechanism 4 that is arranged in a lower portion within the sealed casing 2 and rotated by the above motor 3 to suck and discharge a refrigerant gas.

The compression mechanism 4 includes a cylindrical cylinder 5 that is fitted to an inner surface of the sealed casing 2, a cylindrical rotor 6 that is accommodated within the cylinder 5 such that a portion of an outer circumferential surface 6C is always in contact with an inner circumferential surface 5A of the cylinder 5, a vane 8 that is slidably fitted into a radial guide groove 5B of the cylinder 5 such that a distal end portion is always in contact with the outer circumferential surface 6C of the rotor 6 by a spring 7, and a pair of upper and lower closing members 11 and 12 that close end surfaces 5C and 5D as axial opening portions of the above cylinder 5.

The pair of closing members 11 and 12 are arranged in a state in which the upper and lower end surfaces 5C and 5D of the cylinder 5 are sandwiched from the upper and lower sides, and the cylinder 5 and the two closing members 11 and 12 are integrally coupled together by fastening bolts 13 at a plurality of circumferential positions while maintaining air tightness. Accordingly, a space surrounded by the cylinder 5 and the two closing members 11 and 12 is obtained as a compression space 14, and inner wall surfaces 11A and 12A (thrust surfaces) of the two closing members 11 and 12 facing the compression space 14 are located close to end surfaces 6A and 6B of the rotor 6. The compression space 14 of the cylinder 5 is divided into two adjacent space portions by the vane 8 and the outer circumferential surface 6C of the rotor 6 such that one of the space portions is used as a suction chamber 15 and the other of the space portions is used as a compression chamber 16.

Through holes 11B and 12B are pierced through center portions of the upper and lower closing members 11 and 12, and a drive shaft 3A of the motor 3 passes through the through holes 11B and 12B of the two closing members 11 and 12 while maintaining air tightness, and also passes through the above rotor 6. The drive shaft 3A is pivotally supported so as to be rotatable by the through holes 11B and 12B of the two closing members 11 and 12. Also, the drive shaft 3A has a large-diameter eccentric portion 3B which is located within the rotor 6 and whose axis is radially displaced from the original axis of the drive shaft 3A, and the large-diameter eccentric portion 3B circumferentially slides on an inner circumferential surface of the rotor 6.

When the drive shaft 3A of the above motor 3 is rotated in a predetermined direction, the large-diameter eccentric portion 3B is also rotated, so that the rotor 6 is rotated along the inner circumferential surface 5A of the cylinder 5 in conjunction with the rotation of the large-diameter eccentric portion 3B. At this time, a portion of the outer circumferential surface 6C of the rotor 6 slides in contact with the inner circumferential surface 5A of the cylinder 5, and the distal end of the vane 8 urged by the spring 7 slides in contact with the outer circumferential surface 6C of the rotor 6. Since the volumes of the suction chamber 15 and the compression chamber 16 expand and contract when the rotor 6 is rotated as described above, a refrigerant gas is compressed after being sucked into the suction chamber 15 through a suction port 17, and then, discharged outside of the cylinder 5 (outside of the sealed casing 2) through a discharge port 18 from the compression chamber 16.

Lubricant oil 21 is stored in the lower portion within the sealed casing 2, and is supplied to sliding portions of an inner circumferential surface 6D and the outer circumferential surface 6C of the rotor 6 through an unillustrated oil passage formed within a lower end portion of the drive shaft 3A when the above rotor 6 is rotated. The configuration of the rotary compressor 1 as described above is well known in, for example, Patent Literature 1.

In the present embodiment, the inner wall surfaces 11A and 12A of the two closing members 11 and 12 coupled to the cylinder 5 are improved to suppress a seizure between the opposite end surfaces 6A and 6B of the rotor 6 and the inner wall surfaces 11A and 12A as the thrust surfaces.

That is, shallow circular concave portions 11C and 12C are formed in the inner wall surfaces 11A and 12A of the two closing members 11 and 12 from the through holes 11B and 12B on the center side to regions on the outer circumferential side close to the fastening bolts 13 as shown in an enlarged manner in FIGS. 3 and 4. These concave portions 11C and 12C are set to the same outer diameter, and also set to the same depth. To be more specific, the depth of the concave portions 11C and 12C is set to, for example, 1 μm to 100 μm, and preferably set to 5 μm to 50 μm.

When the cylinder 5 and the two closing members 11 and 12 are coupled together by the plurality of fastening bolts 13, outer rims 11D and 12D of the concave portions 11C and 12C are located radially outward of the inner circumferential surface 5A of the cylinder 5 so as to overlap with the end surfaces 5C and 5D of the cylinder 5.

Synthetic resin coatings 22 and 22 are applied to the entire concave portions 11C and 12C of the two closing members 11 and 12 with a thickness matching the depth of the concave portions 11C and 12C. Thus, the surfaces of the synthetic resin coatings 22 and 22 are flush with the original inner wall surfaces 11A and 12A of the closing members 11 and 12 located outwardly adjacent to the concave portions 11C and 12C.

Moreover, in the present embodiment, annular grooves 22A having the same depth and the same width are concentrically formed at a predetermined radial pitch in the surface of the above synthetic resin coating 22 as shown in FIG. 4. That is, the adjacent annular grooves 22A and annular projections 22B located in abutment therebetween form regular concavities and convexities in the surface of the synthetic resin coating 22.

The annular projections 22B located in abutment between the respective annular grooves 22A define the substantial thrust surface of the synthetic resin coating 22, which is flush with each of the original inner wall surfaces 11A and 12A. In the present embodiment, the width of the above annular groove 22A is set to 20 μm to 500 μm, and preferably set to 50 μm to 300 μm. The depth of the annular groove 22A (the height of the annular projection 22B) is set to 1 to 20 μm, and preferably set to 2 to 10 μm.

A material obtained by adding at least one of graphite, carbon, PTFE, and MoS₂ to a thermosetting synthetic resin is used as the material of the synthetic resin coating 22. While the material as described above is used as the synthetic resin coating material, a hard material such as alumina may be further added to the above material so as to improve the material strength. The annular grooves 22A may be formed not only in the surface of the synthetic resin coating 22, but also partially or entirely in each of the inner wall surfaces 11A and 12A on the radially outer circumferential side of the synthetic resin coating 22.

As described above, in the present embodiment, the shallow concave portions 11C and 12C are formed in the inner wall surfaces 11A and 12A of the closing members 11 and 12, and the concave portions 11C and 12C are entirely coated with the synthetic resin coats 22.

Because of the configuration as described above, the dimensions (the depth, the outer diameter) of the concave portions 11C and 12C, the thickness of the synthetic resin coating 22 or the like can be easily controlled when the above concave portions 11C and 12C are formed in the closing members 11 and 12, and are filled with the synthetic resin coatings 22 and 22 in a manufacturing process of the closing members 11 and 12. In other words, the concave portions 11C and 12C can be filled with the synthetic resin coatings 22 without performing complicated control of the dimensions of the concave portions and the thickness of the synthetic resin coating as in the case of Patent Literature 3 described above.

In accordance with the present embodiment as described above, when the axial dimensions of the cylinder 5 and the rotor 6 are set to desired dimensions and the above respective constituent members are assembled together, a slight gap α is maintained between the end surfaces 6A and 6B of the rotor 6 and the synthetic resin coatings 22 (the thrust surfaces) located close thereto (see FIG. 3). In a compressing process in which the rotor 6 is rotated, the respective constituent components have a difference in thermal expansion due to the high-temperature and high-pressure refrigerant gas and sliding heat generation in the sliding portion of the above rotor 6. Even when the above gap a obtained in the assembling is thereby reduced to bring into contact the end surfaces 6A and 6B of the rotor 6 and the above synthetic resin coatings 22 as the thrust surfaces, the synthetic resin coatings 22 have favorable lubricant oil retention, and compatibility between the end surfaces 6A and 6B and the synthetic resin coatings 22 is also favorable since the plurality of annular grooves 22A as concave portions are formed. Thus, even when the end surfaces 6A and 6B of the rotor 6 and the above synthetic resin coatings 22 as the thrust surfaces come into contact with each other, the annular projections 22B, as the substantial thrust surfaces, located in abutment between the annular grooves 22A of the synthetic resin coatings 22 come into contact with the end surfaces 6A and 6B of the rotor 6. That is, the thrust surfaces have a smaller sliding area as compared to a case in which the entire surfaces of the synthetic resin coatings 22 are formed as flat surfaces. Accordingly, the seizure between the end surfaces 6A and 6B of the rotor 6 and the synthetic resin coatings 22 can be favorably prevented.

Since the synthetic resin coatings 22 have high lubricant oil retention because of the plurality of annular grooves 22A, the sliding heat generation can be reduced by the cooling capacity of the lubricant oil. Since the sliding heat generation can be reduced as described above, the difference in thermal expansion of the respective constituent components can be reduced, so that the gap between the end surfaces 6A and 6B of the rotor 6 and the synthetic resin coatings 22 as the thrust surfaces described above can be set to a small width in the initial setting. Accordingly, the compression efficiency can be improved by suppressing compression leakage of the refrigerant gas from a high-pressure side to a low-pressure side within the compression space 14, and the operation efficiency of the rotary compressor 1 can be eventually improved.

Since the sliding heat generation can be reduced by the lubricant oil retention of the synthetic resin coatings 22 as described above, heat exchange in the suction chamber 15 on a refrigerant gas suction side (low temperature) can be suppressed, and a decrease in volumetric efficiency due to heat transmission to the suction chamber 15 can be prevented. The operation efficiency of the rotary compressor 1 can be improved in this point as well.

Moreover, when MoS₂ is added to the above synthetic resin coatings 22, the lubricant oil retention of the synthetic resin coatings 22 is further improved, so that the seizure can be prevented by the sliding heat generation and low friction by MoS₂.

In the rotary compressor 1, the thrust surfaces are often exposed to a liquid refrigerant due to a liquefaction phenomenon of the refrigerant gas caused by a temperature difference between the day and the night. Since the liquid refrigerant cleans the lubricant oil, the thrust surfaces are brought into a dry environment lacking in the lubricant oil when exposed to the liquid refrigerant. In conventional cases, the seizure phenomenon may thereby occur on the thrust surfaces due to no lubricant oil when the compressor is started. In the present embodiment, however, the thrust surfaces are coated with the synthetic resin coatings 22, so that the seizure on the thrust surfaces, i.e., at the positions of the synthetic resin coatings 22 can be prevented even under the dry environment lacking in the lubricant oil.

Furthermore, by adding PTFE to the above material as the synthetic resin coatings 22, the sliding characteristics of the thrust surfaces (the synthetic resin coatings 22) under the above dry environment can be improved, and higher sliding characteristics can be ensured even under the above dry environment.

A hard additive such as graphite may be also added to the above material as the synthetic resin coatings 22, so that the rigidity of the annular grooves 22A and the annular projections located in abutment therebetween of the synthetic resin coatings 22 can be improved, and favorable sliding characteristics can be thereby obtained.

If the synthetic resin coatings 22 as the thrust surfaces are not provided, the seizure occurs on the end surfaces 6A and 6B of the rotor 6 when a foreign matter enters between the end surfaces 6A and 6B of the rotor 6 made of metal and the inner wall surfaces 11A and 12A of the closing members 11 and 12 made of metal. In the present embodiment, however, since there exist the synthetic resin coatings 22 as the thrust surfaces, the foreign matter is embedded in the synthetic resin coatings 22. Since the synthetic resin coatings 22 have foreign matter embeddability as described above, the seizure of the rotor 6 can be prevented in this point as well in the present embodiment.

Next, FIGS. 5 and 6 show a main portion of a rotary compressor 1 according to a second embodiment to which the present invention is applied, and in the second embodiment, the present invention is applied to a vane-type rotary compressor 1.

That is, the vane-type rotary compressor 1 includes a cylindrical cylinder 5, a columnar rotor 6 that is accommodated therein and rotated by a drive shaft 3A of a motor, three vanes 8 that are provided in a radiation direction at an outer circumferential portion of the rotor 6, and a pair of closing members 11 and 12 that close end surfaces 5C and 5D as front and rear openings of the cylinder 5. The cylinder 5 and the two closing members 11 and 12 are coupled together by a plurality of fastening bolts 13 while maintaining air tightness, and a compression space 14 within the cylinder 5 is divided into three operation chambers 15 by an outer circumferential surface of the rotor 6 and the three vanes 8.

When the drive shaft 3A arranged coaxially with the rotor 6 is rotated, the rotor 6 is also rotated, and distal ends of the three vanes 8 move in contact with an inner circumferential surface 5A of the cylinder 5, so that the three operation chambers 15 expand and contract. A refrigerant gas sucked into the operation chambers 15 from a suction port 17 is thereby compressed, and discharged outside of the cylinder 5 through a discharge port 18. The basic configuration of the second embodiment as described above does not differ from, for example, that of Patent Literature 3 described above.

As shown in FIG. 6, in the second embodiment, concave portions 11C and 12C similar to those of the aforementioned first embodiment are also formed in the two closing members 11 and 12, and synthetic resin coatings 22 are also provided in the concave portions 11C and 12C in a similar manner to the aforementioned first embodiment. Moreover, although not shown in the drawings, a plurality of annular grooves are also formed in the surface of the synthetic resin coating 22 of the second embodiment in a similar manner to the above first embodiment shown in FIG. 3.

In the second embodiment, members corresponding to those of the above first embodiment are assigned the same reference numerals. The rotary compressor 1 of the second embodiment having the above configuration can also produce the same operations and advantages as those of the above first embodiment.

Although the case in which the present invention is applied to the rotary compressor 1 in which the cylindrical rotor 6 and the plate-like vane 8 are separately provided has been described in the above first embodiment, the present invention may be also applied to a rotary compressor 1 in which a rotor 6 to which a vane 8 is integrally fixed to an outer circumferential portion is provided, and a drive shaft 3A of a motor and its eccentric large-diameter portion 3B cause the rotor 6 to swing within a cylinder 5 as shown in FIG. 7. Since the rotary compressor 1 having the configuration as described above is well known in Patent Literature 2 described above, the detailed description thereof is omitted. The above configuration shown in FIG. 3 may be employed as the cylinder 5 and a pair of closing members that close axial front and rear end surfaces of the cylinder 5 in the rotary compressor 1 shown in FIG. 7. In the embodiment shown in FIG. 7, members corresponding to those of the above first embodiment are assigned the same reference numerals.

Also, although the present invention is applied to the rotary compressor 1 in which the inner circumferential surface 5A of the cylinder 5 has a cylindrical shape, and the three vanes 8 are arranged on the outer circumferential surface 6C of the rotor 6 in the above second embodiment shown in FIGS. 5 and 6, the present invention may be also applied to a rotary compressor 1 in which five vanes 8 are provided at an outer circumferential portion of a rotor 6, and a cylinder 5 has an oval shape in section as shown in FIG. 8. The above configuration shown in FIG. 3 may be applied as the cylinder 5 and a pair of closing members that close end surfaces as axial opening portions of the cylinder 5 in the rotary compressor 1 shown in FIG. 8. In the embodiment shown in FIG. 8, members corresponding to those of the above second embodiment are assigned the same reference numerals.

Although the embodiment in which the present invention is applied to the rotary compressor 1 including the three or five vanes 8 is disclosed in FIGS. 5 and 8, the present invention may be applied to a vane-type rotary compressor 1 including at least one vane 8.

Next, FIG. 9 shows yet another embodiment of the present invention. In simple terms, the present invention is applied to a rotary compressor 101 including the above configuration in FIG. 7 in upper and lower stages in the embodiment shown in FIG. 9.

That is, a compression mechanism 104 of the rotary compressor 101 includes an upper closing member 111 that is fitted to a sealed casing 102, a first cylinder 105 whose upper opening is closed by an inner wall surface 111A (a lower surface) of the closing member 111, a disk-shaped intermediate closing member 120 that closes a lower opening of the first cylinder 105, a second cylinder 105′ whose upper opening is closed by a lower surface of the intermediate closing member 120, and a lower closing member 112 that closes a lower opening of the second cylinder 105′.

A space portion surrounded by the first cylinder 105, the closing member 111, and the intermediate closing member 120 is obtained as a first compression space 114, and a first rotor 106 is accommodated therein. A first large-diameter eccentric portion 103B of a drive shaft 103A of a motor 103 is fitted within the first rotor 106 so as to be slidable in a circumferential direction.

Also, a space portion surrounded by the intermediate closing member 120, the second cylinder 105′, and the lower closing member 112 is obtained as a second compression space 114′, and a second rotor 106′ is accommodated therein. A second large-diameter eccentric portion 103B′ of the above drive shaft 103A is slidably fitted within the second rotor 106′.

The upper and lower two closing members 111 and 112, the intermediate closing member 120, and the two cylinders 105 and 105′ are integrally coupled together by a plurality of fastening bolts 113. Since the configuration of the multi-stage rotary compressor 101 as described above is well known in, for example, Japanese Patent Laid-Open No. 2008-280485, the further detailed description is omitted.

A configuration similar to that in FIGS. 3 and 4 is also employed in the rotary compressor 101 having the above configuration at positions facing the two compression spaces 114 and 114′. That is, a concave portion and a resin coating, with which the concave portion is filled, similar to those in FIG. 4 are provided in the inner wall surface (the lower surface) 111A of the upper closing member 111 and an upper surface 120A (an inner wall surface) of the intermediate closing member 120. Also, a concave portion and a resin coating, with which the concave portion is filled, similar to those in FIG. 4 are provided in a lower surface 120B (an inner wall surface) of the intermediate closing member 120 and an inner wall surface (upper) 112A of the lower closing member 112. In the embodiment shown in FIG. 9, respective members corresponding to those in FIGS. 1 and 7 are assigned reference numerals respectively added with 100. The configuration of the present invention shown in FIGS. 3 and 4 can be applied to the two closing members 111 and 112 and the intermediate closing member 120 in the multi-stage rotary compressor 1 as described above.

Although the plurality of annular grooves 22A are provided in the surface of the synthetic resin coating 22 to form the plurality of concave portions in the aforementioned respective embodiments, vertical and horizontal grid-like projections 22C may be formed in the surface of the synthetic resin coating 22 to form regular square concave portions 22D located in abutment within the grid-like projections 22C as shown in a front view of a main portion in FIG. 10. In this case, the respective grid-like projections 22C define a substantial thrust surface.

Moreover, the above plurality of annular grooves 22A may be concentrically formed at different pitches, or a spiral groove may be formed instead of the annular grooves.

In the aforementioned respective embodiments, the entire surface of the synthetic resin coating 22 may be formed as a flat surface without forming the plurality of annular grooves 22A in the surface of the above synthetic resin coating 22.

REFERENCE SIGNS LIST

-   1: Rotary compressor -   2: Sealed casing -   5: Cylinder -   6: Rotor -   11, 12: Closing member -   11C, 12C: Concave portion -   14: Compression space -   22: Synthetic resin coating 

1. A rotary compressor comprising: a cylindrical cylinder that is arranged within a casing; a pair of closing members that close axial front and rear opening portions of the cylinder; a compression space that is formed by the cylinder and the pair of closing members; and a rotor that is accommodated within the compression space so as to be movable in conjunction with a drive shaft, wherein a concave portion is formed in a region facing the compression space in an inner wall surface of each of the closing members, and the concave portion is filled with a synthetic resin coating such that a surface of the synthetic resin coating is flush with the original inner wall surface of the closing member located radially outward thereof, wherein a plurality of annular grooves are concentrically formed at a same radial pitch in the surface of the synthetic resin coating.
 2. The rotary compressor according to claim 1, wherein an outer rim of the synthetic resin coating and an outer rim of the concave portion are located radially outward of an inner circumferential surface of the cylinder, and are in abutment against an axial end surface of the cylinder when the cylinder and the pair of closing members are coupled together by fastening means. 3.-4. (canceled) 